US6991653B2 - Vertebral body and disc space replacement devices - Google Patents

Abstract

A vertebral replacement device for supporting adjacent vertebrae includes a vertebral body member having at least one of an upper or lower disc replacement member engaged thereto at one end thereof. The disc replacement device can be positioned in a spinal disc space when disengaged from the vertebral body member.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The application is a continuation-in-part application of U.S. patent application Ser. No. 10/103,237 filed on Mar. 21, 2002 U.S. Pat. No. 6,758,862.

BACKGROUND

The present invention is directed to devices for replacement of one or more vertebral bodies and/or one or more disc spaces between vertebrae of a spinal column.

The repair and reconstruction of bony structures is sometimes accomplished by directly fixing adjacent bony structures to each other, such as by a plate. In other instances, bone growth inducing material can be introduced between the adjacent bony structures, which over time results in a solid bony connection. In some instances, the adjacent bony structures are not sufficiently strong to maintain their patency as the bone heals or the bone grows between the adjacent structures through the bone growth inducing material. In these instances, mesh structures or cages have been provided to engage the adjacent bony structures to provide additional stability. The cages are generally hollow and can be configured to contact the harder cortical bone of the adjacent bony structures. The hollow portion of the cages can be filled with bone growth inducing material.

Devices have also been provided to replace a removed vertebral body and to provide a support structure between the remaining vertebrae on either side of the one or more removed vertebral bodies. One example of such a device is provided in U.S. Pat. No. 5,192,327.

The '327 patent describes oval or hemi-oval rings which can be used in isolation in a disc space or stacked one upon another in interdigitating fashion for replacement of a vertebral body. The rings have ridges along their top and bottom faces that form peaks and valleys to allow the stacked rings to interdigitate when stacked. One problem with these interdigitating ridges is that the stack of rings can slide relative to one another in the direction of the ridges when stacked. The '327 patent also discloses a connecting bar extending through the stacked rings transversely to the ridges to prevent relative sliding between the stacked rings. In order to use the connecting bar in surgery, the surgeon must be provided with a multitude of bars of differing heights and/or “custom fit” the bar as needed for the height of the particular set of stacked cages. In addition, the stacked cages can separate longitudinally even when the connecting bar extends through the stacked cages.

There remains a need for improved devices for replacing one or more vertebral bodies and/or one or more disc spaces in a spinal column. The present invention is directed to satisfying these needs, among others.

DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a vertebral replacement device according to one embodiment of the present invention.

FIG. 2 is an exploded perspective view of the vertebral replacement device of FIG.1.

FIG. 3 is a side elevation view of the vertebral replacement device ofFIG. 1 in partial section to illustrate the interconnection between disc replacement members and a vertebral body member of the device.

FIG. 4 is an elevational view of an engaging member comprising a portion of the vertebral body member of the device of FIG.1.

FIG. 5 is an end view of the vertebral replacement device of FIG.1.

FIG. 6 is a perspective view of a disc replacement member comprising a portion of the vertebral replacement device of FIG.1.

FIG. 7 is an elevation view of the disc replacement device of FIG.6.

FIG. 8 is an elevational view of the vertebral replacement device ofFIG. 1 positioned in the spinal column between two vertebrae.

FIG. 9 is an elevational view of one of the disc replacement devices comprising a portion of the vertebral replacement device ofFIG. 1 positioned in a spinal disc space between adjacent vertebrae.

FIG. 10 is a perspective view of another embodiment vertebral replacement device.

FIG. 11 is an exploded perspective view of another embodiment vertebral replacement device.

FIG. 12 is a perspective view of a vertebral replacement device according to another embodiment of the present invention.

FIG. 13 is an exploded perspective view of the vertebral replacement device of FIG.12.

FIG. 14 is a side elevation exploded view of the vertebral replacement device of FIG.12.

FIG. 15 is a perspective view looking toward a concavely curved wall of a disc replacement member comprising a portion of the device of FIG.12.

FIG. 16 is a perspective view looking toward a convexly curved wall of the disc replacement member of FIG.15.

FIG. 17 is an elevation view looking at the concavely curved wall of the disc replacement member of FIG.15.

FIG. 18 is an elevation view looking at the convexly curved wall of the disc replacement member of FIG.15.

FIG. 19 is a plan view of the disc replacement member of FIG.15.

FIG. 20 is an end elevation view of the disc replacement member of FIG.15.

FIG. 21 is a plan view of the vertebral replacement device of FIG.12.

FIG. 22 is an elevation view of a vertebral replacement device according to another embodiment of the present invention.

FIG. 23 is an end elevation view of the vertebral replacement device of FIG.22.

FIG. 24 is an elevation view of a vertebral body member comprising a portion of the vertebral replacement device of FIG.22.

FIG. 25 is an end elevation view of the vertebral body member of FIG.24.

FIG. 26 is a plan view of the vertebral body member of FIG.24.

FIG. 27 is a section view of a portion of the vertebral body member of FIG.24 throughline27—27 of FIG.26.

FIG. 28 is a perspective view of a disc replacement member comprising a portion of the vertebral replacement device of FIG.22.

FIG. 29 is a section view of the disc replacement member of FIG.28 throughline29—29.

FIG. 30 is a perspective view of an assembly including a pair of vertebral replacement devices of FIG.22.

FIG. 31 is a perspective view of another embodiment assembly comprising another embodiment of the vertebral replacement device of FIG.22.

FIG. 32 is a perspective view of a portion of another embodiment vertebral replacement device.

FIG. 33 is an elevation view of another embodiment assembly comprising the vertebral replacement device of FIG.32.

FIG. 34 is a plan view of the assembly of FIG.33.

FIG. 35 is an elevation view of a disc replacement member comprising a portion of another embodiment vertebral replacement device.

FIG. 36 is a section view throughline36—36 of FIG.35.

FIG. 37 is a section view along the longitudinal axis of a vertebral body member engageable to the disc replacement member of FIG.35.

FIG. 38 is another section view of the vertebral body member ofFIG. 37 rotated 90 degrees about the longitudinal axis.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the illustrated embodiments thereof and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any such alterations and further modifications in the invention, and any such further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.

The present invention relates to devices for replacing one or more vertebral bodies in the spinal column and/or one or more disc spaces between adjacent vertebrae. It is contemplated that the replacement devices will support adjacent ones of the intact vertebrae during fusion thereof. It is further contemplated that one or more components of the vertebral replacement devices can be positioned in a disc space between adjacent vertebrae for supporting the adjacent vertebrae during fusion thereof. Application in non-fusion procedures is also contemplated

In one embodiment, the device can employ current mesh or cage-type devices for engagement with adjacent bony structures, although other types of bone supporting devices are also contemplated. The vertebral replacement device can have a tubular form with a hollow chamber extending therethrough. The adjacent vertebrae are supported by opposite ends of the device and the chamber can be filled with bone growth inducing or osteogenetic material. The ends of the device include flattened plateau-like end surfaces that can be formed at the junction between bars defining the mesh wall structure of the device.

In one embodiment, the vertebral replacement device includes a connecting member and an upper member attached to an upper end of the connecting member and a lower member attached to a lower end of the connecting member. Each of the members can have a generally kidney bean cross-sectional shape in the plane transverse to the central axis of the assembled device. Other cross-sectional shapes are also contemplated, including circular, racetrack-shaped, rectangular, square, oval, D-shaped, triangular, boomerang, banana, or other polygonal shape. Each of the upper and lower members can include an interior chamber. The connecting member can also include an interior chamber that generally aligns with the interior chambers of the upper and lower members engaged thereto.

In one embodiment, the upper and lower members can be fabricated from a tubular mesh having apertures through its wall. One example of a tubular mesh is provided in U.S. Pat. No. 5,897,556, which is incorporated herein by reference in its entirety. The connecting member can also be fabricated from a tubular mesh. Further forms contemplate that the upper and lower members and connecting member can be a tubular body with solid walls or wall structure including one or more openings.

In one embodiment, the upper and lower members can be telescopically and non-rotatably engaged with the connecting member. The connecting member includes an upper extension and a lower extension extending therefrom. The upper and lower extensions are in the form of substantially continuous rings extending around the respective ends of the vertebral body or connecting member. Other forms for the upper and lower extensions are also contemplated. The upper and lower extensions are received in the interior chamber of the respective upper or lower members when the upper and lower members are engaged to the connecting member. In another embodiment, extensions are provided on the upper and lower members, and these extensions are received in an interior chamber or opening at respective ends of the connecting member.

Each of the upper and lower extensions, and each of the chambers of the upper and lower members, can have a non-circular cross-section and interface to prevent relative rotation between the connecting member and the upper or lower member engaged thereto.

In one embodiment, the upper and lower extensions of the connecting member each include an engaging member which can be flexed inwardly as the respective upper or lower member is placed around the respective extension of the connecting member. The engaging member fits into an opening or aperture in the inner wall surface of the respective upper and lower members to axially secure the respective upper and lower members to the connecting member.

Any one or all of the components of the vertebral replacement devices can be made from any biocompatible material, including synthetic or natural autograft, allograft or xenograft tissues, and can be resorbable or non-resorbable in nature. Examples of tissue materials include hard tissues, connective tissues, demineralized bone matrix and combinations thereof. Further examples of resorbable materials are polylactide, polyglycolide, tyrosine-derived polycarbonate, polyanhydride, polyorthoester, polyphosphazene, calcium phosphate, hydroxyapatite, bioactive glass, and combinations thereof. Further examples of non-resorbable materials are non-reinforced polymers, carbon-reinforced polymer composites, PEEK and PEEK composites, shape-memory alloys, titanium, titanium alloys, cobalt chrome alloys, stainless steel, ceramics and combinations thereof and others as well.

Any suitable osteogenetic material or composition is contemplated for placement within the chambers defined by the components or the vertebral replacement device. Such osteogenic material includes, for example, autograft, allograft, xenograft, demineralized bone, synthetic and natural bone graft substitutes, such as bioceramics and polymers, and osteoinductive factors. Where bony material is placed within the chambers of the components of the vertebral replacement device, the material can be pre-packed into the hollow chambers before the device is implanted, or can be pushed through the plurality of wall openings after the device is in position in the spinal column. A separate carrier to hold the materials within the chambers of the device can also be used. These carriers can include collagen-based carriers, bioceramic materials, such as BIOGLASS®, hydroxyapatite and calcium phosphate compositions. The carrier material can be provided in the form of a sponge, a block, folded sheet, putty, paste, graft material or other suitable form. Moreover, the osteogenetic compositions contained within the vertebral replacement device can comprise an effective amount of a bone morphogenetic protein, transforming growth factor β1, insulin-like growth factor 1, platelet-derived growth factor, fibroblast growth factor, LIM mineralization protein (LMP), and combinations thereof or other therapeutic or infection resistant agent, held within a suitable carrier material.

InFIGS. 1-2, avertebral replacement device10 includes a connectingmember12, anupper member30, and alower member40.Device10 is illustrated as having a tubular form that extends along alongitudinal axis11 and defines a chamber extending therethrough alongaxis11. Bone growth can occur through this chamber for fusion between the vertebral bodies supported at each end ofdevice10.

Connectingmember12 includes abody14 extending between anupper end19 and an oppositelower end21. Connectingmember12 further includes anupper extension18 and alower extension23. Connectingmember12 has an inner wall surface13 (FIG. 5) that defines achamber16 extending between and opening at the outer ends of theextensions18,23. Each of theextensions18,23 extends outwardly from therespective end19,21 ofbody14 and aroundchamber16.End surface15 extends aroundupper extension18, and endsurface17 extends aroundlower extension23. In the illustrated embodiment,extensions18,23 are substantially continuous rings extending from theirrespective end19,21. Other embodiments contemplate other forms for the extensions, such as, for example, a series of two or more flexible engaging members (such as engagingmember20 discussed below) or rigid engaging members.

The wall ofbody14 includes a number oftriangular apertures22 which extend through the wall and communicate withchamber16. Other shapes forapertures22 are also contemplated, including non-circular shapes such as a square, diamond, oval and/or rectangular shapes, circular shapes, and/or polygonal shapes. The wall ofbody14 also includes a number ofholes24 extending at least partially therethrough.Holes24 can be threaded or otherwise sized and/or configured for engagement with one or more insertion instruments (not shown.)

Referring further toFIGS. 3-5, the substantially continuous wall of each of theextensions18,21 is interrupted by an engagingmember20. Only engagingmember20 forupper extension18 is illustrated, it being understood thatlower extension23 can also be provided with an identical or similar engaging member. Engagingmembers20 secureupper member30 andlower member40 to respective ends of connectingmember12, resisting axial dislocation ofupper member30 andlower member40 away from connectingmember12 alongaxis11. Engagingmembers20 can also resist axial rotation of upper andlower members30,40 relative to connectingmember12 aboutaxis11. Other embodiments contemplate that more than one engagingmember20 is provided in the wall of one or both of theextensions18,23. Further embodiments contemplate that wall of one or both of theextensions18,23 is not substantially continuous, but rather is continuous or includes a number of discrete wall portions sufficiently spaced and sized aboutbody14 of connectingmember12 for engagement with upper andlower members30,40.

Engagingmember20 includes a projection or engagingportion52 and astem50 connected or integrally formed withend surface15 ofbody14.Stem50 has a reduced thickness to allow engagingmember20 to deflect inwardly in response to a force applied to engagingportion52. Engagingportion52 projects outwardly fromstem50 and has a triangular shape tapering from an engagingsurface54 to anupper end56. Other configurations for engagingmember20 are also contemplated. For example, engagingmember20 can be provided with an engagingportion52 in the form of a partially spherical or rounded nub, a receptacle, rectangular or polygonal shaped tab or projection. Engagingportion52 can also correspond to the shape theaperture22 in which it is received. Engagingmember20 can also be a snap ring, collet, bayonet lock, or surface irregularity that resists axial movement of the engagedupper member30 andlower member40 away from connectingmember12 alongaxis11.

Referring also toFIGS. 6-7, upper andlower members30,40 are illustrated as being identical, although it is also contemplated thatupper member30 andlower member40 can be provided with different configurations and/or sizes. With respect toFIGS. 6 and 7, onlyupper member30 will be further described, it being understood thatlower member40 can be provided with identical features.

Upper member30 includes abody32 extending between anupper end33 and alower end35.Body32 has aheight82 between the upper and lower ends33,35.Height82 can be selected so thatupper member30 fits within an intervertebral disc space between adjacent vertebrae.Upper end33 andlower end35 can be sloped to converge toward one another and form a height86opposite height82. The sloped ends33,35 allowupper member30 to restore and/or conform to the natural inclination between the adjacent endplates of the vertebral bodies. It is further contemplated that ends33,35 can be parallel to one another.

Body32 has aninner wall surface37 defining achamber34 that extends between and opens at ends33,35. As shown inFIG. 5,body32 has anouter surface39 that defines a kidney-shaped cross section transverse tolongitudinal axis11. Other cross-sectional shapes are also contemplated, including, for example, circular cross-sections and non-circular cross-sections, such as oval, triangular, square, rectangular, polygonal, boomerang shaped, D-shaped, or racetrack shaped cross-sections. In the illustrated embodiment, connectingmember12 has the same cross-sectional shape as the upper andlower members30,40 to provide a vertebral replacement body device of uniform cross-sectional shape and size along its height.

Body32 defines a number oftriangular apertures36 extending at least partially therethrough in communication withchamber34, and a number ofcircular holes38 extending at least partially therethrough from the exterior surface ofbody32.Holes38 or the other holes can be threaded or otherwise sized and/or configured for engagement with one or more insertion instruments.

Body32 further includes a number of bearing surfaces60 spaced aroundfirst end32 and bearingsurfaces62 spaced aroundsecond end35. Adjacent ones of each of the bearing surfaces60 are separated from one another by V-shapedrecesses64. Adjacent ones of each of the bearing surfaces62 are separated from one another by V-shapedrecesses66. Bearing surfaces60,62 are planar and provide a number of plateau-like, generally flat bearing surfaces spaced about the respective end ofbody32. Bearing surfaces60,62 have a trapezoidal shape in the illustrated embodiment, although other shapes are also contemplated. In the illustrated embodiment, ten such bearing surfaces60,62 are provided at each end ofbody32. It is also contemplated that fewer than ten or more than ten bearing surfaces could be provided. It is further contemplated that each end ofbody32 could be provided with a single, continuous bearing surface extending aroundchamber34.

The plateau-like bearing surfaces60,62 provide a surface area about the ends ofbody32 for bearing support of the adjacent vertebral endplate and to resist subsidence ofbody32 into the vertebrae. The plateau-like bearing surfaces60,62 provide surface area contact between the end ofbody32 and the adjacent endplate, providing frictional resistance tobody32 sliding or twisting relative to the adjacent vertebral endplate.

Upper member30 andlower member40 are connected to respective ends of connectingmember12 to provide vertebralreplacement body device10.Upper member30 is advanced overupper extension18 so thatupper extension18 extends intochamber34. Engagingmember20 flexes inwardly asinner wall surface37 ofbody32 passes along engagingportion52. Engagingportion52 is configured to reside within one of theapertures36 extending into the wall ofbody32 fromchamber34. When engagingportion52 and therespective aperture36 are aligned, engagingmember20 returns towards its pre-insertion position with engagingportion52 residing in therespective aperture36. This engagesupper member30 to connectingmember12, resisting movement ofupper member30 away from connectingmember12 alongaxis11. It is further contemplated engagingsurface54 engages the adjacent lower surface of therespective aperture36 to provide a positive seat between bearingsurface15 of connectingmember12 and bearingsurfaces62 aboutend33 ofupper member30.Lower member40 is secured tolower extension23 in a similar manner.

Bearing surfaces62 atlower end35 ofupper member30 bear againstend surface15 extending aboutupper extension18 of connectingmember12. This bearing relationship transmits the spinal column load fromupper member30 to connectingmember12. The bearing surfaces of thelower member40 similarly bear againstend surface17 extending aboutlower extension23 of connectingmember12. The end surfaces15,17 at the end ofbody14 and the adjacent bearing surfaces of the upper andlower members30,40 do not interdigitate. This bearing relationship eliminates stress concentrations and shifting of the components ofdevice10 that might result from improperly aligned interdigitating surfaces.

Axial rotation ofupper member30 andlower member40 relative to connectingmember12 is resisted by the interface between upper andlower extensions18,23 and the respective inner wall surface of the upper andlower members30,40. In the illustrated embodiment,extensions18,23 have a non-circular shape, such as the kidney shape shown in FIG.5. Similarly, theinner wall surface37 ofupper member30 and also the inner wall surface oflower member40 have a non-circular shape sized to receive in form fitting engagement the respective upper orlower extension18,23. This non-circular form fitting engagement prevents rotation ofupper member30 andlower member40 relative to connectingmember12.

Device10 can be used to replace a vertebra that has been removed from the spinal column segment using known techniques.Device10 is assembled by securingupper member30 to one end of connectingmember12 and securinglower member40 to the other end of connectingmember12. This provides avertebral replacement device10 that has an overall height that is equal to the sum of theheights80 ofbody14,height82 ofupper member30, andheight84 of lower member40 (FIG. 3.)

As shown inFIG. 8, thevertebral replacement device10 can be placed betweenvertebra70 andvertebra74 after removal ofvertebra72. Replacement of more than one vertebra is also contemplated. Although not required, it is contemplated thatheight80 could be representative of that of the removed vertebra andheights82,84 could be representative of the heights of the respective disc spaces between the removedvertebra72 and the remainingvertebrae70,74. Also shown inFIG. 8 is astabilization construct150 engaged to and extending betweenvertebrae70 and74 to support and stabilize the spinal column segment before, during and, ifconstruct150 is non-resorbable and left in the patient, after fusion. Stabilization construct150 can be a rod system, plate system or artificial ligament system. It is further contemplated that stabilization system could be attached to any portion ofvertebrae70 and74, including the anterior, antero-lateral, lateral, postero-lateral or posterior portions.

It is also contemplated thatheights82 and84 could be identical or different, and that the ends of upper andlower members30,40 could be provided with the same or differing angles of inclination. It is further contemplated thatdevice10 can comprise a kit having a number ofupper members30 andlower members40 of various sizes andheights82,84. A kit could also include a number of connectingmembers12 of various sizes andheights80. Such a kit would provide the surgeon flexibility in selecting the appropriately size and height for members of adevice10 based on conditions encountered in surgery.

FIG. 9 illustrates placement of one of the upper orlower members30,40 indisc space76 betweenadjacent vertebrae70,72 to function as an interbody fusion device. Engagement of stabilization construct tovertebrae70 and72 is also contemplated.

It is also contemplated that connectingmember12 could be provided with one end configured to bear against a vertebral endplate, and that only one of the upper andlower members30,40 is engaged to the other end of connectingmember12. The assembled device could then be placed between adjacent vertebrae with an end of connectingmember12 and an end of the selected upper orlower member30,40 in contact with the adjacent vertebral endplates.

InFIG. 10 there is provided an alternate embodimentvertebral replacement device100.Device100 includes first disc replacement orupper member30 and second disc replacement orlower member40 engaged at opposite ends of a vertebral body or connectingmember102, which can be similar to connectingmember12 discussed above. Connectingmember102 does not include upper and lower extensions extending fromend104 and105. To secureupper member30 andlower member40 to connectingmember102, asleeve112 is provided around connectingmember102 that has anupper end114 overlappingupper member30 and alower end115 overlappinglower member40.

Sleeve112 can be provided with engagingmembers117,118 in the form of projections, engaging members, tabs or the like on its inner wall surface. Engagingmembers117,118 engageapertures36,46 or other receptacle or detent in the outer wall surfaces ofupper member30 andlower member40, respectively. Engaging members could also be provided to engageapertures106 or other receptacle or detent in connectingmember102. So engaged,sleeve112 resists axial movement ofupper member30 andlower member40 relative to connectingmember102.

It is further contemplated that rotation ofupper member30 andlower member40 relative to connectingmember102 could be prevented by a non-circular, telescoping interface between the members such as discussed above. In another embodiment, rotation ofupper member30 andlower member40 relative to connectingmember102 could be prevented by the engagement ofsleeve112 with the upper andlower members30,40 and, if so configured, with connectingmember102. In yet a further form of the embodiment ofFIG. 10, the connectingmember102 could be integral withsleeve member112 to provide upper and lower bearing surfaces withinsleeve112 for support ofupper member30 andlower member40 thereon.

Referring now toFIG. 11, another embodimentvertebral replacement device210 is shown.Device210 includes a vertebral replacement or connectingmember212 having abody214 extending between anupper end219 and alower end221.Upper end219 includes anupper extension218 having anend surface215 therearound.Extension218 extends around abearing surface216 at the upper end ofchamber220.Bearing surface216 is positioned belowend surface215 inchamber220.Second end217 similarly includes anextension223 having anend surface217, and a bearing surface (not shown) at the lower end ofchamber220 belowend surface217.

A first disc replacement orupper member230 includes abody232 having anupper end233 and alower end235.Body232 extends around achamber234. A second disc replacement orlower member240 includes abody242 having alower end243 and anupper end245.Body242 extends around achamber244.Lower member240 includes aninset wall248 extending aroundchamber244, and a bearing surface250 extending aroundbody242 belowinset wall248.Upper member230 similarly includes aninset wall238 and a bearing surface (not shown) extending aroundbody232 aboveinset wall238.

When assembled,inset wall238 ofupper member230 is received inchamber220 of connectingmember212 withextension218 extending aroundinset wall238. Similarly,inset wall248 oflower member240 is received inchamber220 of connectingmember212 withextension223 extending aroundinset wall248. It contemplated thatend surface215 can contact the bearing surface extending aroundinset wall238, and thatend surface217 can contact bearing surface250 extending aroundinset wall248. Additionally or alternatively, the lower end ofinset wall238 can contactbearing surface216 inchamber220 at the upper end of connectingmember212, and the upper end ofinset wall248 can contact the bearing surface (not shown) inchamber220 at the lower end of connectingmember212.

Connectingmember212 and/or upper andlower members230,240 could be provided with engaging members or a sleeve such as discussed above to prevent axial and/or rotational movement of upper andlower members230,240 relative to connectingmember212 whendevice210 is assembled. In a further embodiment, connectingmember212 does not include theupper bearing surface216 and the lower bearing surface inchamber220 sinceextensions218,223 are not provided on connectingmember212. In this embodiment,inset walls238 and248 are received inchamber220 at the respective end of connectingmember212, and endsurfaces215,217 contact respective ones of the bearing surfaces extending aroundinset walls238,248.

Referring now toFIGS. 12-21, there is shown another embodimentvertebral replacement device300.Vertebral replacement device300 includes one or more upper or lower end ordisc replacement members400,401 and one or more connecting orvertebral body members310 engaged todisc replacement members400,401.Vertebral replacement device300 has application in corpectomy procedures in which one or more vertebrae are removed, and in interbody fusion procedures where the device is positioned in a spinal disc space. In the illustrated embodiment,vertebral replacement device300 includes three members stacked one upon the other. Other embodiments contemplate vertebral replacement devices comprising two members stacked one upon the other, and vertebral replacement devices comprising four or more members stacked one upon the other.

It is contemplated thatvertebral body member310 can be provided as a single unit or in multiple sections coupled to one another.Disc replacement members400,401 can be engaged at opposite ends ofvertebral body member310. It is further contemplated that one end ofvertebral body member310 can be configured to contact a vertebral endplate, and the opposite end engaged with adisc replacement member400,401 to form a two member stack. It is also contemplated that a pair ofvertebral body members310 can be engaged to respective upper and lower ends of a singledisc replacement member400,401. The ends of thevertebral body members310 opposite thedisc replacement member400,401 can be configured to engage a vertebral endplate, or configured for engagement with a seconddisc replacement member400,401.

InFIGS. 12-14vertebral replacement device300 extends alonglongitudinal axis302 includesvertebral body member310 having abody312. A first or upperdisc replacement member400 is engaged at an upper end of abody312 and a second or lowerdisc replacement member401 is engaged at a lower end ofbody312.Body312 extends between anupper end surface314 and alower end surface315. In the illustrated embodiment, end surfaces314,315 include a concave curvature in at least one direction transverse tolongitudinal axis302 to provide a solid bearing relationship with an adjacent convex surface of thedisc replacement member400,401 positioned thereagainst.

Body312 includes a wall extending betweenupper end surface314 andlower end surface315. The wall includes, in one contemplated implantation orientation, ananterior portion330 and anopposite posterior portion332. Opposite side or endportions334,336 extend between and interconnectanterior portion330 andposterior portion332. Other implantation orientations are contemplated wherewalls330,332,334,336 have other orientations relative to the patient. In the illustrated embodiment, end surfaces include smooth, uninterrupted surface profile that includes a first concave curvature betweenanterior portion330 andposterior portion332 as shown inFIG. 14, and a second concave curvature betweenend portions334,336, as shown in FIG.13. The double concavity matches the surface profile of the end surface of thedisc replacement member400,401 positioned thereagainst. The surface profile of the end surface of thedisc replacement member400,401 can be selected to provide the desired fit with the patient's anatomy at the vertebral endplates.

In one form,body312 includes a boomerang or banana shaped cross-section transverse tolongitudinal axis302, such as shown in FIG.21. In this form,anterior wall portion330 is convexly curved along its outer surface andposterior wall portion332 is concavely curved along its outer surface.End wall portions334,336 are convexly curved and offset posteriorly relative toanterior portion330, such as discussed withrespect replacement member400 below. Other shapes forbody312 are also contemplated such as discussed above with respect todevice10. The illustrated shape ofvertebral replacement device300 facilitates positioning in a space between vertebrae along a curved insertion path from a posterior-lateral approach such that, when finally positioned, bilateral support of the vertebrae is provided byvertebral replacement device300.

Body312 includes agroove326 extending therearound mid-height alonganterior wall portion330 and endwall portions334,336. Groove326 can facilitate attachment to an insertion instrument having an engagement portion adapted for positioning ingroove326. It is also contemplated thatbody312 can be provided withoutgroove326. It is further contemplated thatbody312 can be provided with one or more threaded openings, non-threaded openings, one or more receptacles or other structure for engagement of an insertion instrument withbody312.

Body312 can include number of openings through its wall portions in communication with one or more chambers inbody portion312. In the illustrated embodiment,body312 includesopenings328 ingroove326.Additional openings324 are provided inanterior wall portion330 above and belowgroove326. Openings can also be provided inposterior wall portion332 and/or endwall portions334,336 ofbody312. In the illustrated embodiments,openings324 are elongated and form an oval or racetrack shape alonglongitudinal axis302.Openings328 can also be elongated in the direction oflongitudinal axis302 and extend between the upper and lower sides ofgroove326. Theelongated openings326,328 maximize communication between the internal chamber or chambers ofbody312 and the exterior ofbody312 to facilitate bony incorporation ofbody312 during fusion with bone growth material inbody312 and the bone growth material outsidebody312. Other embodiments contemplate thatbody312 can be provided with any number of wall openings in any shape, including circular, triangular, polygonal or curved openings. It is also contemplated thatbody312 can be provided without any wall openings.

Posterior portion332 of the wall ofbody312 can includes one or more receptacles that are identical in shape toreceptacles444,448 ofend member400 as discussed below. Such receptacles can extend along all or a portion of the length ofbody312 betweenends314,315.

Vertebral body member310 includes a first engagingmember320 extending fromupper end surface314 alongaxis302, and a second engagingmember321 extending fromlower end surface315 alongaxis302. Engagingmembers320,321 can be identical to one another, and are described with reference to engagingmember320. Engagingmember320 includes a projection or engagingportion352 and astem350 connected or integrally formed withend surface314 ofbody312.Stem350 can include a thickness that allows engagingmember320 to deflect inwardly towardlongitudinal axis302 in response to a force applied to engagingportion352. Engagingportion352 projects outwardly fromstem350 away fromlongitudinal axis302 in the illustrated embodiment. Engagingportion352 includes a triangular shape tapering from a lowerengaging surface354 to anupper end356, as shown in FIG.13. Engaging portion can also slope towardaxis302 from engagingsurface354 toupper end356, as shown inFIG. 14, to facilitate passage of the disc replacement member thereover.

Other configurations for engagingmembers320,321 are also contemplated. For example, engagingmembers320,321 can be provided with an engagingportion352 in the form of a partially spherical or rounded nub, a receptacle, rectangular or polygonal shaped tab or projection. Engagingportion352 can also correspond to the shape of the aperture, recess or other receptacle in which it is received when engaged to the correspondingdisc replacement member400,401. Engagingmembers320,321 can also be a snap ring, collet, bayonet lock, or surface irregularity that resists axial movement of the engageddisc replacement member400,401 away fromvertebral body member310 alongaxis302.

Vertebral body member310 includes a firstupper extension316 and a secondupper extension318 extending fromupper end surface314 in the direction oflongitudinal axis302.Vertebral body member310 also includes a firstlower extension317 and a secondlower extension319 extending fromlower end surface315 in the direction oflongitudinal axis302. These extensions are received in chambers of the adjacentdisc replacement members400,401 and contact inner wall surfaces to resist lateral and rotational displacement of thedisc replacement members400,401 relative tovertebral body member310.

Referring further toFIGS. 15-20, further details regardingdisc replacement members400,401 will be further discussed with reference todisc replacement member400. While it is contemplated thatdisc replacement members400,401 can be identical to one another, identity is not required. It is also contemplated that only onedisc replacement member400 can be provided for removable engagement withvertebral body member310. In addition to use withvertebral body member310 as a vertebral replacement device,disc replacement member400 can be separated fromvertebral body member310 and positioned in a spinal disc space as an interbody spacer. It is contemplated thatdisc replacement member400 can be provided with a hollow interior or one or more openings that can be packed with bone growth material or other known substance and inserted into the disc space to promote bony fusion between adjacent vertebrae.Disc replacement member400 can also be used in non-fusion procedures, or in fusion procedures where bone growth through the member is not contemplated.

Disc replacement member400 can be provided with a boomerang or banana shape that is suited for insertion from a postero-lateral or uni-lateral approach into the disc space. It is also contemplated thatdisc replacement member400 can be inserted in the disc space using any other techniques and instruments and other approaches to the disc space, such as lateral, anterior or antero-lateral approaches. While it is contemplated thatvertebral body member312 anddisc replacement member400 have the same shape when viewed alonglongitudinal axis302, differing shapes for each member are also contemplated.

Disc replacement member400 includes a body having afirst end portion450, asecond end portion452, and amiddle portion454 therebetween. When inserted into a disc space, for example, from a posterior-lateral approach, either of theend portions450,452 can be a leading end and the other a trailing end, depending on the orientation ofdisc replacement member400 and the direction of insertion. Aconcave posterior wall402 and an opposite convexanterior wall404 extend alongmiddle portion454, and also along at least part of the corresponding side offirst end portion450 andsecond end portion452.Disc replacement member400 further includes an arcuate convexly curvedfirst end wall406 extending alongfirst end portion450 betweenposterior wall402 andanterior wall404.Disc replacement member400 also includes an arcuate convexly curvedsecond end wall408 extending alongsecond end portion452 betweenposterior wall402 andanterior wall404.Disc replacement member400 further includes afirst end surface410 and an oppositesecond end surface412 extending betweenwalls402,404,406 and408.

Disc replacement member400 has afirst height90 at the medial portion ofposterior wall402 and asecond height92 at the medial portion ofanterior wall404.First end surface410 andsecond end surface412 have a convex curvature between the posterior andanterior walls402,404.Second height92 is greater thenfirst height90 in order to correspond to the anatomy of the vertebral endplates on each side of the disc space at the contemplated insertion location fordisc replacement member400.First end wall406 andsecond end wall408 each include aheight94 that is less than first andsecond heights90,92.First end surface410 andlower end surface412 have a convex curvature betweenfirst end wall406 andsecond end wall408 as best shown inFIGS. 17-20. This double convex curvature substantially matches the double concave curvature of the adjacent vertebral endplates. Furthermore, the difference in heights between the upper and lower end surfaces at the anterior and posterior walls can be provided so as to establish lordosis whendisc replacement member400 is inserted in the disc space. Other embodiments contemplate thatsurfaces410,412 include a single convex curvature, or more than two convex curvatures.

First end surface410 can further be provided with a number offirst grooves414 alonganterior wall404 andsecond grooves415 along first andsecond end walls406,408.Second end surface412 can be provided with a number offirst grooves416 alonganterior wall404 andsecond grooves417 along first andsecond end walls406,408.Grooves414,415 andgrooves416,417 increase frictional resistance between the adjacent vertebral endplate and the end surfaces410,412 to resist posterior and anterior migration ofdisc replacement member400 in the disc space.

In order to provide avenues for bone growth throughdisc replacement member400, the walls ofdisc replacement member400 can be provided with a number of chambers opening atfirst end surface410 andsecond end surface412. In particular,first end portion450 includesfirst chamber418 andsecond end portion452 includessecond chamber420.Middle portion454 includes amiddle chamber422. Afirst strut424 is located betweenfirst chamber418 andmiddle chamber422 and extends betweenposterior wall402 andanterior wall404. Asecond strut426 is located betweensecond chamber420 andmiddle chamber422 and extends betweenposterior wall402 andanterior wall404.

As further shown inFIG. 21,middle chamber422 includes a triangular shape with the anterior apex of the triangle in communication withopening428 alonganterior wall404. Engagingmember320 is positionable in the apex ofmiddle chamber422 so that engagingportion352 engages inopening428. It is contemplated that at leastengaging surface354 of engagingportion352 engageswall404 at the bottom of opening428 to resist movement ofdisc replacement member400 away fromvertebral body member310 alongaxis302.

First andsecond chambers418,420 include an elongated ovoid shape sized to receiveextensions316,318 therein adjacent a posterior wall of the chamber. Accordingly, engagingmember320 extends along an inner surface ofanterior wall404, andextensions316,318 are each offset from engagingmember320 on the opposite sides ofcentral axis405 to contact inner surfaces ofposterior wall402 and/or endwalls406,408 to resist rotation ofdisc replacement member400 aboutlongitudinal axis302.Vertebral body member310 includes a first chamber orpassage331 in communication withfirst chamber418, a second chamber orpassage333 in communication withsecond chamber420, and a central chamber orpassage335 in communication withmiddle chamber422.Chambers331,333,335 can extend throughvertebral body member310 between end surfaces314,315 to provide avenues for bone growth.

In the illustrated embodiment,extensions316,318 are cylindrical posts sized and shaped to be intimately received in posterior portions ofchambers418,420. Engagingmember320 is a cylindrical post with a triangular cross-section for receipt in the anterior apex ofchamber422. Other embodiments contemplate other forms for engagingmember320 andextensions316,318. For example,extensions316,318 could be sized to substantially occupy the entire first andsecond chamber418,420 in which it is positioned. Additional extensions could be provided fromvertebral body member310 that are positionable inmiddle chamber422. In another form, one or more of thestruts424,426 could be eliminated, and one or more extensions provided that extend along a portion or substantially along the entire inner wall surface ofdisc replacement member400. Alternatively or additionally to the illustratedextensions320, one ormore extensions320 could be positioned aboutend surface314 for engagement with other openings in the walls ofdisc replacement member400.

Referring back toFIGS. 15-20, additional details regardingdisc replacement member400 will be discussed.Posterior wall402 includes aposterior opening427 alongmiddle portion454, andanterior wall404 includes ananterior opening428 alongmiddle portion454. In the illustrated embodiment, posterior wall opening427 is circular and anterior wall opening428 is oval or racetrack shaped and elongated in the direction betweenupper end surface410 andlower end surface412; however, other shapes foropenings427,428 are also contemplated, including circular and non-circular shapes.First end portion450 includes first andsecond wall openings430,431 inanterior wall404, andsecond end portion452 includes first andsecond wall openings432,433 inanterior wall404. In the illustrated embodiment,openings430,431 and432,433 are oval or racetrack shaped and elongated in the direction betweenfirst end surface410 andlower end surface412; however, other shapes foropenings430,431 and432,433 are also contemplated.

Anterior wall404 includes an offsetportion434 that is offset anteriorly with respect to the remaining portions ofanterior wall404 extending from either side thereof. Anterior offsetportion434 provides additional bearing support area for the vertebrae and additional strength and rigidity to the body ofdisc replacement member400. A number ofradiographic markers438 can also be provided indisc replacement member400 to facilitate X-ray assessment of the locating and positioning ofdisc replacement member400 in the patient's body. Such markers are particularly useful for adisc replacement member400 made from radiolucent material. In the illustrated embodiment,markers438 are provided at the midline ofanterior wall404 at the anterior-most point defined by offsetportion434.Markers438 are also provided at the posterior-most points offirst end wall406 andsecond end wall408. Positioningmarkers438 at these locations provides an indication of the anterior and posterior placement ofdisc replacement member400 in the disc space, and also an indication of the lateral placement ofdisc replacement member400 in the disc space. Alignment of theend wall markers438 in a lateral X-ray indicates proper orientation ofdisc replacement member400 in the disc space in the A-P direction.

Disc replacement member400 includes a recessedarea446 extending alongfirst end wall406 and a portion ofanterior wall404.Disc replacement member400 also includes a recessedarea442 extending alongsecond end wall408 and a portion ofanterior wall404. Recessedareas442,446 are located in the respective wall portions mid-height betweenupper bearing surface410 andlower bearing surface412. Recessedsurfaces442,446 are configured to receive a portion of an implant insertion instrument and to facilitate grasping of the implant, as discussed further below.

The symmetrical shape ofdisc replacement member400 allowsdisc replacement member400 to be inserted into the disc space from a unilateral approach taken on either side of the spinous process, and by grasping either offirst end portion450 orsecond end portion452 with an insertion instrument.Disc replacement member400 is provided with a first inserterinstrument engaging receptacle444 atfirst end portion450 and a second inserterinstrument engaging receptacle448 atsecond end portion452. Each of the engagingreceptacles444,448 are configured along with adjacent recessedareas442,446 for engagement with an implant inserter instrument.Body312 can similarly be provided with receptacles aligned withreceptacle444,448 in the stacked configuration that can be engaged with an implant insertion instrument.

Examples of insertion instruments for insertingdisc replacement members400,401 and/orvertebral replacement device300 are provided in U.S. patent application Ser. No. 10/120,104, which is incorporated herein by reference in its entirety.First end wall406 andsecond end wall408 could also include a threaded hole for engagement with an inserter. In the illustrated embodiment, engagingreceptacles444,448 are in the form of grooves that extend betweenfirst end surface410 andsecond end surface412. Each of the grooves is aligned with a corresponding one of thefirst strut424 andsecond strut426.First strut424 andsecond strut426 provide bearing support to resist application of forces applied to the implant wall by an insertion instrument positioned in the respective engagingreceptacle444,448.

Vertebral replacement device300 includes anaxis405 extending through its center in the direction betweenfirst end wall406 andsecond end wall408, as shown in FIG.21.Axis405 is equal distance from the most posterior point onfirst end wall406 and the most posterior point onsecond end wall408.First end wall406 is offset to the posterior side ofaxis405, andsecond end wall408 is offset to the posterior side ofaxis405. Similarly,axis405 is equal distance from the most posterior point on firstend wall portion334 and the most posterior point on secondend wall portion336 ofbody312. The offset in the first and second ends ofdisc replacement member400 andvertebral body member310 facilitates the controlled insertion ofvertebral replacement device300 along a curved insertion path.

Referring now toFIGS. 22-23, there is shown another embodimentvertebral replacement device500.Vertebral replacement device500 includes one or more upper or lower end ordisc replacement members600,601 and one or more connecting orvertebral body members510 engaged todisc replacement members600,601.Vertebral replacement device500 has application in corpectomy procedures in which one or more vertebrae are removed. Applications in disc space replacement and interbody fusion procedures are also contemplated. In the illustrated embodiment,vertebral replacement device500 includes three members stacked one upon the other. Other embodiments contemplate two member stacks, or stacks comprising four or more members.

It is contemplated thatvertebral body member510 can be provided as a single unit or in multiple sections coupled to one another.Disc replacement members600,601 can be engaged at opposite ends ofvertebral body member510. It is further contemplated that one end of thevertebral body member510 can be configured to contact a vertebral endplate, and the opposite end engaged with adisc replacement member600,601. It is also contemplated that a pair ofvertebral body members510 can be engaged to respective upper and lower ends of adisc replacement member600,601. The ends of thevertebral body members510 opposite thedisc replacement member600,601 can be configured to engage a vertebral endplate, or configured for engagement with a seconddisc replacement member600,601.

Referring further toFIGS. 24-26,vertebral replacement device500 extends alonglongitudinal axis502 and includesvertebral body member510 having abody512. A first or upperdisc replacement member600 is engaged at an upper end ofbody512 and a second or lowerdisc replacement member601 is engaged at a lower end ofbody512.Body512 extends between anupper end surface514 and alower end surface515.Body512 includes walls extending betweenupper end surface514 andlower end surface515. The walls include afirst end wall530 and an oppositesecond end wall532. Oppositeside walls534,536 extend between and interconnectfirst end wall530 andsecond end wall532.

In one form,body512 includes a generally rectangular shape transverse tolongitudinal axis502, such as shown in FIG.26. In the illustrated embodiment, endwalls530,532 are generally parallel with one another, andside walls534,536 are generally parallel with one another. Adjacent walls can be connected with beveled portions or curved portions to eliminate abrupt edges between the walls at the corners ofbody512. Other shapes forbody512 are also contemplated as discussed herein. In one application,side walls534,536 are oriented in the anterior-posterior direction whendevice10 is positioned between vertebrae.End walls530,532 are shorter thanside walls530,532 such that the width of betweenside walls534,536 is less than the half of the supported vertebral endplates in the medial-lateral direction. Accordingly, bi-lateral support of the vertebrae is provided by positioning a pair ofvertebral replacement devices10 in the space between the vertebrae with theside walls534,536 of each device oriented in the anterior-posterior direction. Other applications contemplate thatside walls534,536 can be positioned in other orientations in the space between vertebrae, including medial lateral orientations and oblique orientations.

Upper and lower end surfaces514,515 each include a surface profile that facilitates stacking ofdisc replacement members600,601 thereon to provide a stable stacking arrangement. In the illustrated embodiment,upper end surface514 ofbody512 includes a concave curvature betweenend walls530,532. Similarly,lower end surface515 includes a concave curvature betweenend walls530,532. Upper and lower end surfaces514,515 are not curved betweenside walls534,536. Upper and lower end surfaces514,515 are smooth and do not include surface interruptions. As shown inFIGS. 22-23,disc replacement members600,601 include a convex curvature that allows the disc replacement member to be fully supported by the respective end surfaces514,515 betweenend walls530,532 andside walls534,536. Other embodiments contemplate other configurations for upper and lower end surfaces514,515 as discussed herein.

Body512 can include number of openings through its wall structure in communication with one ormore chambers526 inbody512. In the illustrated embodiment,body512 includes a pair ofopenings528 inside wall534.Openings528 are positioned on opposite sides ofaxis302, and oneopening528 is offset towardend surface514 and the other opening is offset towardend surface515.Side wall536 can be provided with similarly located openings. Openings can also be provided inend walls530,532, such asopening524 shown inend wall532. In the illustrated embodiments, opening524 is centrally positioned inend wall532. It is contemplated that any one or combination of theopenings524,528 can be threaded, non-threaded and/or non-circular. Any one or combination of theopenings524,528 can be engaged with an insertion instrument to facilitate insertion ofvertebral replacement device500 in the space between vertebrae.Chamber526 extends throughbody512 and opens at end surfaces514,515. Theopenings524,528 can communicate withchamber526 to provide avenues for bone growth through the wall ofbody512. Other embodiments contemplate thatbody512 can be provided with any number of openings in any shape, including circular, non-circular, triangular, polygonal or curved openings. It is also contemplated thatbody512 can be provided without any openings.Body512 can also be provided without achamber526, but rather a solid body structure.Body512 can further be provided with multiple chambers or openings extending therethrough between end surfaces514,515.

Vertebral body member510 includes engagingmembers520,521 extending fromupper end surface514 adjacent respective ones of theside walls534,536. Similarly, engagingmembers523,525 extend fromlower end surface515 adjacent respective ones of theside walls534,536. Engagingmembers520,521,523,525 include a reduced thickness and are aligned with the inner wall surface ofbody512 definingchamber526. Accordingly, end surfaces514,515 extend along the outer side of engagingmembers520,521,523,525.

Engagingmembers520,521,523,525 can be identical to one another, and like elements are designated with the same reference numerals. Engagingmembers520,521,523,525 each include astem550 connected or integrally formed with therespective end surface514,515 ofbody512 as shown inFIG. 27. A projection or engagingportion552 extends outwardly from thestem550.Stem550 can include a reduced thickness relative to the wall with which it is formed to allow engagingmembers520,521,523,525 to deflect inwardly toward the adjacent engaging member in response to a force applied to engagingportion552. Engagingportion552 projects outwardly toward the respective adjacent side wall fromstem550. Engagingportion552 includes a truncated cylindrical shape, as best shown inFIGS. 24-27.Truncated portion553 of engagingportion552 facilitates passage of adisc replacement member600,601 thereover. Engagingportion552 includes anengaging surface554 that contacts the side wall ofdisc replacement member600,601 in theadjacent hole624,624 to resist axial displacement of the disc replacement member

Other configurations for engagingportions552 are also contemplated, such as a partially spherical or rounded nub, a receptacle, rectangular or polygonal shaped tab or projection. The portion of engagingportion552 oppositetruncated portion553 can correspond to the shape the side wall aperture ofdisc replacement member600,601 in which it is received. Engagingmembers520,521,523,525 can also include a snap ring, collet, bayonet lock, or surface irregularity that resists axial movement of the engageddisc replacement member600,601 away fromvertebral body member510 alongaxis502.

Vertebral body member510 includesupper extensions560,562 extending fromupper end surface514 adjacent respective ones of theend walls530,532.Vertebral body member510 further includeslower extensions564,566 extending fromlower end surface515 adjacent respective ones of theend walls530,532. As discussed further below,extensions560,562,564,566 are positionable in the chamber of the adjacentdisc replacement member600,601 to provide lateral and torsional stability when thedisc replacement member600,601 is stacked onvertebral body member510.

Referring now toFIGS. 28 and 29,disc replacement member600,601 will be further discussed.Disc replacement members600,601 can be secured tovertebral body member510, and are adapted for insertion in isolation into a spinal disc space between adjacent vertebrae to promote fusion of the vertebrae and restore disc space height.Disc replacement members600,601 can be identical, and include anelongate body602 defining alongitudinal axis608, afirst end portion604, and asecond end portion606. At least one ofend portions604,606 includes opposed upper and lower bearing surfaces adapted to bear against the endplates of the supported vertebrae. In one embodiment,body602 is provided to have a substantially rectangular cross-section when viewed in section in the direction oflongitudinal axis608.

Body602 includescentral portion603 that extends fromfirst end portion604 tosecond end portion606.Body602 includes anupper surface610 and an oppositelower surface612 definingchamber614 therebetween.Upper surface610 andlower surface612 can be convexly curved alonglongitudinal axis608 substantially mate with the natural curvature of corresponding facing endplate surfaces of adjacent vertebrae. Thus, the convex configuration ofupper surface610 andlower surface612 facilitates locating thedisc replacement members600,601 approximately in the anterior-posterior middle of the endplate of the adjacent vertebral body. The convex upper andlower surfaces610,612 can inhibit expulsion of the surgically implantedmember600,601 by providing a maximum height that is greater than the height of a surgically prepared entrance to the spinal disc space. In the illustrated embodiment,upper surface610 andlower surface612 are provided with a number of arcuateconcave portions642longitudinal axis608, although a smooth surface profile is also contemplated.

Further,upper surface610 includes at least oneopening616 extending intochamber614. Similarly,lower surface612 includes at least oneopening617 intochamber614. The perimeter of both the upper andlower surfaces610,612 is substantially continuous and uninterrupted.Chamber614 is provided to receive a graft of osteogenetic material, such as spongy bone or other material favoring bone growth, including synthetic bone media. Therefore, the curvilinear configuration ofupper surface610 andlower surface612 and their associatedopenings616,617 allow interpenetration of the cancellous bone revealed in the surgically prepared intervertebral space of adjacent vertebrae. Interpenetration of the cancellous bone of the vertebra enhances the intimate contact and interdiffusion of osteogenic material initially deposited inchamber614 with the cancellous bone tissue and greatly enhances the potential for bone growth.

Body602 can also includeparallel side walls620 and622 extending betweenupper surface610 tolower surface612, and betweenend portions604,606.Side walls620 and622 can includeopenings624 and625, respectively, providing communication intochamber614 to further enhance interdiffusion of the osteogenic material inchamber614 with cancellous bone tissue and material outsidechamber614. Theopposite openings624,625 are also engageable by respective ones of the engagingmembers520,521 or engagingmembers523,525 whendisc replacement member600,601 is stacked on the corresponding end ofvertebral body member510. It is contemplated thatupper surface610 andlower surface612 provide a substantially uniform height fromside wall620 toside wall622 in when viewed orthogonally tolongitudinal axis608. Other embodiments contemplateside walls620,622 that define an uneven height forbody602 orthogonally tolongitudinal axis608.

First end portion604 includes afirst bearing surface628, an oppositesecond bearing surface630, and afirst end wall632 extending therebetween. First bearingsurface628 andsecond bearing surface630 can engage surfaces of cortical bone endplates on adjacent vertebral bodies. When inserted within a prepared intervertebral space,first bearing surface628 andsecond bearing surface630 bear against cortical bone tissue proximate to the posterior portion of the vertebral space.Second end portion606 includes afirst bearing surface634, an oppositesecond bearing surface636, and afirst end wall638 extending therebetween. First bearingsurface634 andsecond bearing surface636 engage surfaces of cortical bone endplates on adjacent vertebral bodies. Ion one application, when inserted within the prepared intervertebral space first bearingsurface634 andsecond bearing surface636 bear against cortical bone tissue proximate to the anterior portion of the intervertebral space. Bearing surfaces628,630,634,636 can sustain the compressive forces associated with normal activity and resist receding into the sponge-like cancellous bone tissue of the vertebral body.Surfaces610,612,628,630,634,636 can be planar, curved or otherwise configured to conform to the profile of the vertebral anatomy against which it is to be positioned. The desired disc height can be maintained for an extended time period while bone fusion progresses. The bearing surfaces can be tapered or offset alonglongitudinal axis608 to provide a desired angle between the vertebrae, or can be non-tapered.

The upper bearing surfaces ofbody602 include anti-expulsion features640, formed byarcuate grooves642 in the upper surfaces ofbody602. The lower bearing surfaces ofbody602 include anti-expulsion features644, formed byarcuate grooves646 in the lower surfaces ofbody602. In one embodiment,grooves642,646 extend transversely tolongitudinal axis608.

First end portion604 includes tool-engagingportion648. Tool-engagingportion648 can be provided with a variety of features adapted to engage an insertion tool for insertion of disc replacement devices into the space between vertebrae. For example, tool-engagingportion648 can include a variety of indents and openings, which may or may not be threaded, to engage correspondingly configured features on an insertion instrument and/or manipulation accessory (not shown) to facilitate implantation and/or movement ofdisc replacement member600,601 in the space between vertebrae.Second end portion606 includes tool-engagingportion650. Tool-engagingportion650 can be provided with a variety of features adapted to engage an insertion tool for insertion of disc replacement devices into the space between vertebrae. For example, tool-engagingportion650 can include a variety of indents and openings, which may or may not be threaded, to engage correspondingly configured features on an insertion instrument and/or manipulation accessory (not shown) to facilitate implantation and/or movement ofdisc replacement member600,601 in the space between vertebrae from an approach opposite that used withtool engaging portion648.

Disc replacement members600,601 can be assembled withvertebral body member510, as shown inFIGS. 22 and 23, to providevertebral replacement device500. Engagingmembers520,522 extend intochamber614 and engage side wall holes624,625, respectively, with engagingportions552. Thetruncated portions553 of engagingportions552 facilitate passage of the inner surface ofside walls620,622 along the outwardly facing surfaces of engagingportions552, and deflect engagingmembers520,521 inwardly toward one another. When engagingportions552 are aligned with the respectiveside wall openings624,625, engagingmembers520,521 return toward their pre-stacked configuration and engage the adjacent side wall opening624,625 to axially securedisc replacement member600 tovertebral body member510 and resist movement ofdisc replacement members600,601 away fromvertebral body member510.Disc replacement member601 is similarly secured to engagingmembers523,525 at the opposite end ofvertebral body member510.

When stacked onvertebral body member510, thelower bearing surface612 ofdisc replacement member600 is supported byupper end surface514, and theupper bearing surface610 ofdisc replacement member601 is supported bylower end surface515. Anti-expulsion features644 ofdisc replacement member600 bear against and are supported byupper end surface514, and anti-expulsion features640 ofdisc replacement member601 bear against and are supported bylower end surface515. The bearing relationship resists axial movement ofdisc replacement members600,601 towardvertebral body member510.Grooves642,646 are spaced from the respective end surfaces514,515 and provide avenues for bone growth betweenvertebral body member510 anddisc replacement members600,601.

In addition to the stability provided by engagingmembers520,520,523,525, rotational or torsional stability betweendisc replacement members600,601 andvertebral body member510 is provided withextensions560,562,564,566.Extension560 contacts theinner wall surface607 ofdisc replacement member600 adjacentsecond end portion606, andextension562 contacts the inner wall surface605 ofdisc replacement member600 adjacentfirst end portion604. The arcuate, semi-circular configuration ofextensions560,562 also provides contact with the inner wall surface alongside walls620,622 ofdisc replacement member600. Accordingly, lateral and rotational displacement of thedisc replacement member600 relativevertebral body member510 is resisted by contact between the inner walls surfaces ofdisc replacement member600 andextensions560,562.Disc replacement member601 is similarly engaged withextensions564,566 to provide lateral and rotational stability withvertebral body member510.

Vertebral replacement devices500 can be placed in isolation in a space between vertebrae, or multiple vertebral replacement devices can be positioned in a space between adjacent vertebrae. In some applications, the multiplevertebral replacement devices500 can be secured to one another to provide further stability. Referring now toFIG. 30, avertebral replacement system580 includes a pair ofvertebral replacement devices500 positioned adjacent one another.Vertebral replacement devices500 are coupled to one another with connectingsystems582,584. Connectingsystems582,584 can each be in the form of a plate having a number of apertures located to receivefasteners586,588,590 to secure the respective plates to opposite ends ofvertebral replacement devices500. Connectingsystems582,584 also have application with the other vertebral replacement devices discussed herein.

In the illustrated embodiment, connectingsystem582 includes apertures through the plate to receivefasteners586 to engage thetool engagement portions648 at one end ofdisc replacement member600 of each of thevertebral replacement devices500. Connectingsystem584 can be also provided with apertures through the plate to receivefasteners586 to engage the oppositetool engaging portion650 ofdisc replacement member600.Fasteners590 are received through apertures of the plate of connectingsystem502 to engage thetool engagement portion648 at one end ofdisc replacement member601 of each of thevertebral replacement devices500. Connectingsystem584 can be provided with apertures and fasteners to engage the oppositetool engaging portion650 ofdisc replacement members601.Fasteners588 are positioned through apertures of the plate of connectingsystem582 to engageopenings524 at one end ofvertebral body member510 of each of thevertebral replacement devices500. Connectingsystem584 can also be provided with apertures and fasteners to engage an opposite opening ofvertebral replacement members510.

Vertebral replacement system580 includes aspace592 betweenvertebral replacement devices500 to provide a bone fusion path.Space592 can be provided in addition to or in lieu of the chambers extending throughvertebral replacement devices500. Alternatively, a third vertebral replacement device can be positioned inspace592 and secured to connectingsystems582,584 withmiddle fasteners586,588,590.

InFIG. 31 there is shown another embodimentvertebral replacement system680 similar tovertebral replacement system580 that includes a pair of side-by-sidevertebral replacement devices700 connected with connectingsystems582,584.Vertebral replacement devices700 include another embodimentvertebral body member710 and oppositedisc replacement members600,601.Vertebral replacement member710 can be identical tovertebral body member510 discussed above, but includes anotherembodiment engaging members720,721,723, and also a fourth engaging member (not shown). Engagingmembers720,721,723 are engaged to the upper and lower surfaces ofdisc replacement members600,601. It is contemplated that a singlevertebral replacement device700 can be used in isolation in a space between vertebrae. Two or morevertebral replacement devices700 can also be positioned in a space between vertebrae without connectingsystems582,584.

Engagingmembers720,721,723 each include an engagingportion730 that extends through thecentral chamber614 of thedisc replacement members600,601 and engages the adjacentupper surface610 ofdisc replacement member600 and thelower surface612 ofdisc replacement member601. Engagingportions730 include a pair of side byside tabs732 positionable in respective ones of thegrooves642 alongupper surface610 orgrooves646 alonglower surface612.Tabs732 can each include a taperedupper surface733 extending from an outer end thereof to facilitate passage of thedisc replacement member600,601 thereover and to inwardly deflect the engagingmembers720,721,723 asdisc replacement members600,601 are moved therealong. When assembled,disc replacement member600 includeslower surface612 positioned againstupper end surface714 ofvertebral body member710. A lower engagement surface of engagingmember732 extends along the adjacentupper surface610 alongside walls620,622 to axially securedisc replacement member600 tovertebral body member710.Disc replacement member601 is similarly secured to the lower end ofvertebral body member710.

Referring toFIG. 32, another embodimentvertebral replacement device800 includes another embodimentvertebral body member810 engaged todisc replacement member600.Vertebral body member810 can be similar tovertebral body member510, and like elements are designated with the same reference numerals.Vertebral body member810 includes afirst flange812 extending upwardly fromupper end surface514 alongside wall534 and asecond flange814 extending upwardly fromupper end surface514 alongside wall536. The lower end ofvertebral body member810 can similarly be provided withflanges816,818 (FIG. 33) alongside walls534,536.

When stacked onvertebral body member810,side walls620,622 ofdisc replacement member600 are received between engagingmembers520,521 and theadjacent flange812,814.Flanges812,814 can engage or contact the outer surface ofside walls620,622 to provide stability for the assembledvertebral replacement device800 by resisting lateral movement and rotational movement of thedisc replacement members600,601 relative tovertebral body member810. The overall width betweenside walls534,536 ofvertebral body member510 can be greater than the width betweenside walls620,622 ofdisc replacement members600,601 to accommodateflanges812,814,816,818.

Referring toFIGS. 33,34, a pair ofvertebral replacement devices800 are connected with anotherembodiment connecting system860. Connectingsystem860 also has application with the other embodiment vertebral replacement devices discussed herein. Connectingsystem860 includesrods862,864,866 and a fourth rod (not shown) belowrod864 in FIG.34 and behindrod866 inFIG. 33 extending between and coupled with the adjacentmedial side walls534,536 of thevertebral body members810. Connectingsystem860 provides stability to the pair of vertebral replacement devices to assist in maintainingdevices800 in the inserted position in a space between vertebrae. Other numbers of rods for connectingsystem860 are also contemplated, including a single rod, two rods, three rods, or five or more rods.

Various coupling mechanisms at the ends ofrods862,864,866 are contemplated. In the illustrated embodiment, ends863 ofrod862, for example, include a resilient collet-type end that includes a number of fingers with enlarged ends that inwardly deflect for insertion into an opening in theside walls534,536. With the enlarged end portions of the resilient fingers in the chamber ofvertebral body member510, the resilient fingers thereafter return toward their pre-insertion configuration to engage thecorresponding side wall534,536. Other connections betweenside walls534,536 androds862,864,866 are also contemplated, including threaded engagement, snap fits, friction or interference fits, welded or fused connections, and combinations thereof.

FIGS. 35-36 show another embodiment for disc replacement members130,140 that are similar todisc replacement members30,40 discussed above. Accordingly, like elements are designated with like reference numerals. The disc replacement members130,140 include abody32 extending between upper and lower ends33,35. A number of upper bearing surfaces160 are provided aboutupper end33, and a number of lower bearing surfaces162 are provided aboutlower end35.Bearing surface160,162 can be similar to bearingsurfaces60,62 discussed above, but are convexly curved so that bearingsurfaces160,162 can conform to a concave curvature of an adjacent vertebral endplate.

Body32 can also be provided with an upperradiographic marker166 and a lowerradiographic marker168 to facilitate visualization of members130,140 in the patients body shouldbody32 be comprised of radiolucent material. Furthermore,upper surfaces160 andlower surfaces162 can be tapered so that one side ofbody32 has a height greater than the other, conforming disc replacement members130,140 to a desired angulation between the vertebral endplates

Section views ofvertebral body member120 are shown inFIGS. 37,38.Vertebral body member120 can be identical tovertebral body member12 discussed above, except thatvertebral body member120 can be for engagement with upper and lower disc replacement members130,140.Vertebral body member120 is attachable to upper and lower disc replacement members130,140 to form a vertebral replacement device.Vertebral body member120 includes anupper end surface165 against which lower bearing surfaces162 of upper disc replacement member130 are positioned. Anupper extension18 and engagingmember20 facilitate axial engagement of the upper disc replacement member130 thereto.Vertebral body member120 further includes alower end surface167 against which upper bearing surfaces160 of lower disc replacement member140 are positioned. Alower extension23 and engagingmember20 facilitate axial engagement of the lower disc replacement member140 thereto.

End surfaces165,167 each include a concavely curved profile that matches the convexly curved profile formed by bearingsurfaces160,162 so that each of the bearing surfaces160,162 are substantially supported by a respect one of the end surfaces165,167 when upper and lower disc replacement members130,140 are secured tovertebral body member120.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. All changes and modifications that come within the spirit of the invention are desired to be protected.

Claims (72)

1. A vertebral replacement device, comprising:

a first member adapted for positioning in a spinal disc space and including a first end surface for engaging an endplate of an adjacent vertebral body and an opposite second end surface; and

a second member comprising an upper end including an upper end surface and a lower end including a lower end surface, said second end surface of said first member positionable adjacent one of said upper end surface and said lower end surface and engageable to said second member with a flexible engaging member extending between said second member and said first member.

2. The device ofclaim 1, wherein:

said first member includes a wall extending between said first end surface and said second end surface and a chamber opening at said second end surface; and

said second member includes said flexible engaging member extending from said one of said upper end surface and said lower end surface positionable in said chamber and engageable to said wall to resist axial movement of said first member away from said second member.

3. The device ofclaim 2, wherein said second member includes at least one extension extending from said one of said upper end surface and said lower end surface, said at least one extension positionable in said chamber to resist rotation of said first member relative to said second member about a longitudinal axis of said second member.

4. The device ofclaim 3, wherein said wall of said first member includes a convexly curved portion, an opposite concavely curved portion, and a pair of opposite convexly curved end portions extending between said convexly curved portion and said concavely curved portion.

5. The device ofclaim 4, wherein said engaging member engages said convexly curved portion and said at least one extension comprises a pair of extensions positionable in said chamber and engageable to respective ones of said convexly curved end portions.

6. The device ofclaim 5, wherein said chamber comprises:

a central chamber between convexly curved portion and said concavely curved portion of said wall; and

a pair of end chambers adjacent respective ones of said convexly curved end portions of said wall, wherein said engaging member is positionable in said central chamber and said pair of extensions are each positionable in a respective one of said pair of end chambers.

7. The device ofclaim 6, wherein said pair of extensions are offset from said engaging member toward said concavely curved portion.

8. The device ofclaim 2, wherein said engaging member includes a post integrally formed with said second member and a protrusion extending from said post toward said wall at an end of said post opposite said one of said upper end and said lower end.

9. The device ofclaim 8, wherein said protrusion is positionable in an opening in said wall when said first member is engaged to said second member.

10. The device ofclaim 8, wherein said chamber includes a triangular shape and said post is positionable in an apex of said triangularly-shaped chamber.

11. The device ofclaim 1, wherein said one of said upper end surface and said lower end surface includes a first concave curvature and said second end surface includes a first convex curvature conforming to said first concave curvature.

12. The device ofclaim 11, wherein said one of said upper end surface and said lower end surface includes a second concave curvature transverse to said first concave curvature and said second end surface includes a second convex curvature transverse to said first convex curvature to said second concave curvature.

13. The device ofclaim 1, wherein said one of said upper end surface and said lower end surface includes a substantially smooth surface profile and said second end surface includes at least one bearing surface bearing thereagainst.

14. The device ofclaim 1, further comprising a third member adapted for positioning in a spinal disc space and including a first end surface for engaging an endplate of an adjacent vertebral body and an opposite second end surface, said second end surface of said third member positionable adjacent the other of said upper end surface and said lower end surface of said second member, said third member engageable to said second member with a flexible engaging member extending between said second member and said third member.

15. The device ofclaim 14, wherein each of said upper end surface and said lower end surface of said second member includes a first concave curvature and said second end surfaces of each of said first and third members includes a first convex curvature conforming to said first concave curvature of said adjacent upper end surface and said lower end surface of said second member.

16. The device ofclaim 15, wherein each of said upper end surface and said lower end surface of said second member includes a second concave curvature transverse to said first concave curvature and said second end surfaces of each of said first and third members includes a second convex curvature transverse to said first convex curvature conforming to said second concave curvature.

17. The device ofclaim 1, wherein:

said flexible engaging member is adapted to resist displacement of said first and second members away from one another; and

displacement of said first member and said second member toward one another is resisted by bearing contact between said one of said upper end surface and said lower end surface of said second member with said second surface of said first member.

18. The device ofclaim 1, wherein:

said first member includes a chamber extending therethrough opening at said first end surface and said second end surface; and

said second member includes a chamber extending therethrough opening at said upper end surface and said lower end surface in communication with said chamber of said first member.

19. The device ofclaim 18, wherein:

said first member includes an anterior wall, a posterior wall, and a pair of opposite end walls extending therebetween, said first member further comprising a pair of struts extending between said anterior wall and said posterior wall, said pair of struts dividing said chamber of said first member into three chambers; and

said second member includes three chambers extending between and opening at said upper end surface and said lower end surface, each of said three chambers of said second member being aligned with and in communication with a respective one of said three chambers of said first member when said first member is engaged to said second member.

20. The device ofclaim 19, further comprising a third member adapted for positioning in a spinal disc space and including a first end surface for engaging an endplate of an adjacent vertebral body and an opposite second end surface, said second end surface of said third member positionable adjacent the other of said upper end surface and said lower end surface of said second member and engageable to said second member with a flexible engaging member extending between said second member and said third member, said third member including an anterior wall, a posterior wall, and a pair of opposite end walls extending therebetween, said third member further comprising a pair of struts extending between said anterior wall and said posterior wall, said pair of struts dividing said chamber of said third member into three chambers each of which is alignable with a respective one of said three chambers of said second member when said third member is engaged thereto.

21. The device ofclaim 1, wherein said first member and said second member each include a chamber and further comprising bone growth material in each of said chambers.

22. The device ofclaim 21, wherein said bone growth material includes one or more selected from group consisting of: bone morphogenetic protein, transforming growth factor β1, insulin-like growth factor 1, platelet-derived growth factor, fibroblast growth factor, and LIM mineralization protein (LMP).

23. The device ofclaim 21, wherein said bone growth material is provided in a carrier having a form selected from the group consisting of: a sponge, a block, folded sheet, putty, and paste.

24. The device ofclaim 1, wherein said first member and said second member each include a boomerang-shaped cross-section transverse to a longitudinal axis of the vertebral replacement device.

25. The device ofclaim 1, wherein the vertebral replacement device includes a longitudinal axis extending therethrough and said first member and said second member each include a kidney-shaped cross-section transverse to said longitudinal axis.

26. The device ofclaim 1, wherein the vertebral replacement device includes a longitudinal axis extending therethrough and said first member and said second member each include a rectangular-shaped cross-section transverse to said longitudinal axis.

27. The device ofclaim 1, wherein said first member and said second member are comprised of resorbable material selected from the group consisting of: hard tissues, connective tissues, demineralized bone matrix, polylactide, polyglycolide, tyrosine-derived polycarbonate, polyanhydride, polyorthoester, polyphosphazene, calcium phosphate, hydroxyapatite, bioactive glass, and combinations thereof.

28. The device ofclaim 1, wherein said first member and said second member are comprised of non-resorbable material selected from the group consisting of: non-reinforced polymers, carbon-reinforced polymer composites, PEEK, PEEK composites, shape-memory alloys, titanium, titanium alloys, cobalt chrome alloys, stainless steel, ceramics and combinations thereof.

29. The device ofclaim 1, wherein:

said first member includes a wall extending between said first end surface and said second end surface, said wall extending about a chamber opening at said second end surface; and

said at least one engaging member extends from said one of said upper end surface and said lower end surface of said second member, said at least one engaging member positionable in said chamber and engageable to said second member to resist axial movement of said first member relative to said second member.

30. The device ofclaim 29, wherein said second member includes a pair of opposite flexible engaging members extending from said one of said upper end surface and said lower end surface, each of said engaging members positionable in said chamber and engageable to said wall of said first member to resist axial movement of said first member relative to said second member.

31. The device ofclaim 29, further comprising at least one extension extending from said one of said upper end surface and said lower end surface of said second member, said at least one extension positionable in said chamber to resist movement of said first member relative to said second member transversely to a longitudinal axis of said second member.

32. The device ofclaim 31, wherein said at least one extension comprises a pair of extensions opposite one another and positionable in said chamber to engage opposite ends of said wall of said first member.

33. The device ofclaim 32, wherein said pair of extensions are cylindrical posts.

34. The device ofclaim 31, wherein said wall of said first member includes concavely curved portions at opposite ends of said chamber, said pair of extensions each including a convex curvature adapted to engage said concavely curved portions of said wall.

35. The device ofclaim 29, wherein said chamber comprises a central chamber and a pair of end chambers on opposite sides of said middle chamber, wherein said engaging member is positionable in said central chamber and further comprising a pair of extensions extending from said one of said upper end surface and said lower end surface, said extensions positionable in respective ones of said pair of end chambers.

36. The device ofclaim 29, wherein said at least one engaging member comprises a pair of engaging members, each engaging member being integrally formed with said second member and extending from said one of said upper end surface and said lower end surface of said second member, each engaging member including a protrusion extending outwardly therefrom toward said first member.

37. The device ofclaim 36, wherein each of said protrusions includes a truncated portion tapering toward and outer end of said engaging member.

38. The device ofclaim 36, wherein each of said engaging members includes a plate-like tab integrally formed with said second member, said plate-like tab having a wall thickness that is less than a wall thickness of said second member adjacent said tab.

39. The device ofclaim 36, wherein each of said protrusions is located at an end of said engaging members opposite said one of said upper end surface and said lower end surface, said engaging members extending through said chamber and said protrusion engaging said first end surface of said first member when said first member is engaged to said second member.

40. The device ofclaim 36, wherein each of said protrusions includes an engaging surface oriented toward said one of said upper end surface and said lower end surface and a tapered surface opposite said engaging surface to facilitate passage of said first member over said engaging member.

41. A vertebral replacement device, comprising:

a first member adapted for positioning in a spinal disc space and including a first end surface for engaging an endplate of an adjacent vertebral body and an opposite second end surface, wherein said second end surface is convexly curved; and

a second member comprising an upper end including an upper end surface and a lower end including a lower end surface, said second end surface of said first member positionable adjacent one of said upper end surface and said lower end surface, said one of said upper end surface and said lower end surface including a concave curvature adapted to bear against the convexly curved second end surface of said first member.

42. The device ofclaim 41, wherein said one of said upper end surface and said lower end surface of said second member is concavely curved between opposite end walls of said second member, and said second end surface of said first member is convexly curved between opposite end walls of said first member alignable with said end walls of said second member.

43. The device ofclaim 42, wherein said second member includes opposite side walls extending between said opposite end walls, said opposite side walls being at least twice as long as said opposite end walls.

44. The device ofclaim 43, wherein said opposite side walls of said second member are parallel to one another and said opposite end walls of said second member are parallel to one another.

45. The device ofclaim 42, wherein said one of said upper end surface and said lower end surface of said second member is concavely curved between opposite side walls of said second member, said opposite side walls extending between said opposite end walls of said second member, and said second end surface of said first member is convexly curved between opposite side walls of said first member alignable with said side walls of said second member.

46. The device ofclaim 41, wherein said one of said upper end surface and said lower end surface of said second member is concavely curved between opposite side walls of said second member, and said second end surface of said first member is convexly curved between opposite side walls of said first member alignable with said side walls of said second member.

47. The device ofclaim 41, wherein said first member is engageable to said second member with a flexible engaging member extending between said second member and said first member.

48. The device ofclaim 47, wherein said engaging member resists movement of said first member away from said second member along a longitudinal axis of the device.

49. The device ofclaim 48, further comprising at least one extension extending between said first member and said second member adapted to resist movement of said first member relative to said second member transversely to the longitudinal axis of the device.

50. The device ofclaim 41, wherein said first end surface of said first member includes a convex curvature adapted to conform to the curvature of the adjacent vertebral endplate.

51. The device ofclaim 50, wherein said first end surface and said second end surface of said first member include the same convex curvature.

52. The device ofclaim 41, wherein said other of said upper end surface and said lower end surface includes a concave curvature and further comprising a third member adapted for positioning in spinal disc space and including a first end surface for engaging an endplate of an adjacent vertebral body and an opposite second end surface, wherein said second end surface of said third member is convexly curved and positionable adjacent said other of said upper end surface and said lower end surface of said second member.

53. The device ofclaim 52, wherein said first end surface of each of said first and third members includes a convex curvature adapted to conform to the curvature of the adjacent vertebral endplate.

54. The device ofclaim 53, wherein said first end surface and said second end surface of each of said first and third members includes the same convex curvature.

55. The device ofclaim 41, wherein said first member and said second member include a rectangular cross-section transverse to said longitudinal axis.

56. The device ofclaim 41, wherein said first member and said second member include a boomerang-shaped cross-section transverse to said longitudinal axis.

57. The device ofclaim 41, wherein said first member and said second member include a kidney-shaped cross-section transverse to said longitudinal axis.

58. A vertebral replacement system, comprising:

a first vertebral replacement device, comprising:

a disc replacement member having a first end surface for engaging an endplate of an adjacent vertebral body and an opposite second end surface;

a vertebral body member comprising an upper end including an upper end surface and a lower end including a lower end surface, said second end surface of said disc replacement member positionable adjacent one of said upper end surface and said lower end surface and engageable to said vertebral body member;

a second vertebral replacement device, comprising:

a disc replacement member having a first end surface for engaging an endplate of an adjacent vertebral body and an opposite second end surface;

a vertebral body member comprising an upper end including an upper end surface and a lower end including a lower end surface, said second end surface of said disc replacement member positionable adjacent one of said upper end surface and said lower end surface and engageable to said vertebral body member; and

a connecting system extending between and securing said first vertebral replacement device to said second vertebral replacement device.

59. The system ofclaim 58, wherein said first vertebral replacement device and said second vertebral replacement device each include a flexible engaging member extending between said vertebral body member and said disc replacement member to secure said vertebral body member and said disc replacement member to one another.

60. The system ofclaim 58, wherein said connecting system includes at least one rod extending between and secured to adjacent side walls of said vertebral replacement devices.

61. The system ofclaim 60, wherein said connecting system includes at least one rod extending between said vertebral body members adjacent said upper ends of said vertebral body members and at least one rod extending between said vertebral body members adjacent said lower ends of said vertebral body member.

62. The system ofclaim 58, wherein said first and second vertebral replacement devices are secured to one another with a space therebetween, said space providing an avenue for bone growth between said first and second vertebral replacement devices.

63. The system ofclaim 62, wherein each of said first and second vertebral replacement devices include a chamber extending therethrough opening at upper and lower ends thereof, said chambers providing avenues for bone growth through said first and second vertebral replacement devices.

64. The system ofclaim 58, wherein said connecting system includes a pair of plates extending between and coupled to respective ones of opposite end walls of said first and second vertebral replacement devices.

65. The system ofclaim 58, wherein:

said first vertebral replacement device further comprises a second disc replacement member having a first end surface for engaging an endplate of an adjacent vertebral body and an opposite second end surface, said second disc replacement member engageable to said vertebral body member with said second end surface positionable adjacent the other of said upper end surface and said lower end surface of said vertebral body member; and

said second vertebral replacement device comprises a second disc replacement member having a first end surface for engaging an endplate of an adjacent vertebral body and an opposite second end surface, said second disc replacement member engageable to said vertebral body member with said second end surface positionable adjacent the other of said upper end surface and said lower end surface of said vertebral body member.

66. A vertebral replacement device, comprising:

a disc replacement member including a body comprising opposing end portions and opposing side walls extending between said opposing end portions, said body further including opposite upper and lower surfaces; and

a vertebral body member removably engageable to said disc replacement member, said vertebral body member comprising a body including opposing end portions and opposing side walls extending between said opposing end portions, said body further including an end surface positionable against one of said upper and lower surfaces of said disc replacement member when engaged thereto, at least one of said side walls of said vertebral body member includes a flange projecting from said end surface and extending along an outer surface of an adjacent one of said side walls of said disc replacement member when engaged thereto.

67. The device ofclaim 66, wherein each of said side walls of said vertebral body member includes a flange projecting from said end surface and extending along an outer surface of a corresponding one of said side walls of said disc replacement member engaged thereto.

68. The device ofclaim 66, wherein said vertebral body member further comprises a flexible engaging member extending from said end surface and positionable in a chamber of said disc replacement member, said one side wall of said disc replacement member being positioned between said flange and said engaging member of said vertebral body member when said disc replacement member is engaged thereto.

69. The device ofclaim 66, wherein:

each of said side walls of said vertebral body member includes a flange projecting from said end surface and extending along an outer surface of a corresponding one of said side walls of said disc replacement member engaged thereto; and

said vertebral body member further comprises a flexible engaging member extending from said end surface at each of said side walls of said vertebral body member and positionable in a chamber of said disc replacement member, said side walls of said disc replacement member being positioned between corresponding ones of said flanges and said engaging members of said vertebral body member when said disc replacement member is engaged thereto.

70. The device ofclaim 69, wherein:

said vertebral body member further comprises a pair of extensions extending from said end surface at each of said end walls of said vertebral body member and positionable in said chamber of said disc replacement member, said extensions engaging adjacent ones of said end portions of said disc replacement member.

71. The device ofclaim 66, wherein:

a second disc replacement member removably engageable to said vertebral body member opposite said disc replacement member, said second disc replacement member including a body comprising opposing end portions and opposing side walls extending between said opposing end portions, said body further including opposite upper and lower surfaces; and

said body of said vertebral body member further including a second end surface opposite said end surface, said second end surface positionable against one of the upper and lower surfaces of said second disc replacement member when engaged thereto, at least one of said side walls of said vertebral body member includes a second flange projecting from said second end surface and extending along an outer surface of an adjacent one of said side walls of said second disc replacement member when engaged thereto.

72. The device ofclaim 71, wherein said vertebral body member further comprises a flexible engaging member extending from said end surface and a second flexible engaging member extending from said second end surface, each of said flexible engaging members positionable in a chamber of said disc replacement member engaged thereto, one of said side walls of each of said disc replacement members being positioned between respective ones of said flanges and said engaging members of said vertebral body member when said disc replacement members are engaged to one another.

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